1. Field of the Invention
The present invention relates to a technique for printing images by forming dots on a print medium during main scanning, and more particularly to a technique for determining an adjustment value for correcting the recording misalignment of dots in the direction of main scanning.
2. Description of the Related Art
Colorprinters having a head for ejecting several color inks are currently used on a wide scale as the output devices for computers. Some color printers print images by ejecting ink drops from nozzles to form dots on a print medium during main scanning.
In a printing operation in which ink drops are ejected from nozzles to form dots on the print medium, the recording positions of the dots sometimes become misaligned due to the backlash of the drive mechanism in the direction of main scanning, the warping of the platen that supports the print medium from below, and the like. The method disclosed in JP 5-69625A, filed by the present applicant, is known as an example of a technique aimed at preventing such misalignments. According to this conventional technique, adjustment values designed to cancel out the misalignment of dot formation in the direction of main scanning are registered in advance, and the recording positions in the forward and reverse passes are corrected based on these adjustment values.
Some color printers have a so-called bidirectional printing feature whereby ink drops are ejected both in the forward pass and reverse pass of main scanning in order to increase the printing speed. The aforementioned correction method can be used to prevent formed dots from being misaligned in the forward and reverse passes during such bidirectional printing. The aforementioned correction method can also be used to prevent formed dots from being misaligned among a plurality of nozzles during so-called unidirectional printing, in which ink drops are ejected only in either forward pass or reverse pass of main scanning.
With such conventional correction methods, however, it is difficult to provide optimal settings aimed at preventing printed images from acquiring graininess due to misaligned dot formation.
An object of the present invention, which was devised in order to overcome the above-described shortcomings of the prior art, is to achieve high efficiency in setting an adjustment value for adjusting a recording misalignment in the direction of main scanning when ink drops are ejected from nozzles to form dots on a print medium.